I know quite a few people who do climbing as a first date but that is not something I enjoy. I am definitely more in the camp or lets go get a drink and figure out if we like each other before committing to spending time in a climbing gym, or a full day outside together. Or some other easy activity as a first date. But not climbing. Is climbing popular in NZ? I'm aware of some amazing climbing in Australia, but not so much in NZ.
That's very fair, committing a lengthy event with someone you don't know just yet! I know of a few people that get into climbing here, but only the indoors setups. Though that's likely more my social circles not including it than it not being popular, I suspect there are many people further inland with the mountains that like to scale things!